Coil component and method of manufacturing the same

Abstract

One object is to improve the insulation between conductor patterns without reducing the effective permeability. A magnetic base body according to one embodiment includes: a coil conductor provided in the magnetic base body so as to extend around a coil axis; a first external electrode electrically connected to one end of the coil conductor; and a second external electrode electrically connected to another end of the coil conductor. The coil conductor includes a first conductor pattern and a second conductor pattern opposed to the first conductor pattern in a first direction along the coil axis. The magnetic base body includes a first region and a second region, the first region containing a plurality of metal magnetic particles, the second region containing composite oxide particles containing Fe, Ni, and Zn, the second region being magnetic and insulating and being interposed between the first conductor pattern and the second conductor pattern.

What is claimed is: 
     
         1 . A coil component comprising:
 a magnetic base body;   a coil conductor provided in the magnetic base body so as to extend around a coil axis;   a first external electrode electrically connected to one end of the coil conductor; and   a second external electrode electrically connected to another end of the coil conductor,   wherein the coil conductor includes a first conductor pattern and a second conductor pattern opposed to the first conductor pattern in a first direction along the coil axis, and   wherein the magnetic base body includes a first region and a second region, the first region containing a plurality of metal magnetic particles, the second region containing composite oxide particles containing Fe, Ni, and Zn, the second region being magnetic and insulating and being located to interpose between the first conductor pattern and the second conductor pattern.   
     
     
         2 . The coil component of  claim 1 , wherein a second resistivity indicating a volume resistivity of the second region is larger than a first resistivity indicating a volume resistivity of the first region. 
     
     
         3 . The coil component of  claim 1 , wherein a second permeability indicating a magnetic permeability of the second region is larger than a first permeability indicating a magnetic permeability of the first region. 
     
     
         4 . The coil component of  claim 1 , wherein a dimension of the second region in the first direction is 3 μm or smaller. 
     
     
         5 . The coil component of  claim 1 ,
 wherein a bottom surface of the first conductor pattern is opposed to a top surface of the second conductor pattern, and   wherein the second region covers an entirety of the bottom surface of the first conductor pattern.   
     
     
         6 . The coil component of  claim 1 , wherein an end of the second region is exposed from the magnetic base body. 
     
     
         7 . The coil component of  claim 1 , wherein the second region is in contact with at least the first conductor pattern. 
     
     
         8 . The coil component of  claim 7 , wherein the second region is in contact with both the first conductor pattern and the second conductor pattern. 
     
     
         9 . The coil component of  claim 1 , wherein as viewed from a direction of the coil axis, an area of the second region is larger than both an area of the first conductor pattern and an area of the second conductor pattern. 
     
     
         10 . The coil component of  claim 1 ,
 wherein the plurality of metal magnetic particles contain Cr, and   wherein the magnetic base body contains ZnCr 2 O 4  at an interface between the first region and the second region.   
     
     
         11 . The coil component of  claim 1 , wherein in a sectional surface of the magnetic base body cut along a cutting plane passing through the coil axis, an area occupied by the second region is 1% to 10% of an area of the sectional surface. 
     
     
         12 . The coil component of  claim 1 , wherein the second region is also located between the second conductor pattern and the first external electrode and between the second conductor pattern and the second external electrode. 
     
     
         13 . A method of manufacturing a coil component, comprising the steps of:
 forming a plurality of laminated sheets each including a green first magnetic sheet and a green second magnetic sheet, the green first magnetic sheet containing a magnetic powder, the green second magnetic sheet covering at least a part of a top surface of the green first magnetic sheet and containing Fe 2 O 3  powder, ZnO powder, and NiO powder;   forming a conductor pattern on a top surface of each of the plurality of laminated sheets so as to cover at least a part of the green second magnetic sheet;   stacking the plurality of laminated sheets to form a laminate;   heating the laminate to form a magnetic base body; and   providing an external electrode on the magnetic base body.   
     
     
         14 . The method of manufacturing a coil component according to  claim 13 , wherein the laminate is heated at a temperature of 800° C. to 1000° C. 
     
     
         15 . The method of manufacturing a coil component according to  claim 13 , wherein in the step of heating, ZnCr 2 O 4  is produced at an interface between the green first magnetic sheet and the green second magnetic sheet.